1. Field of the Invention
The present invention relates generally to methods and apparatus for introducing a stent to into a region of a major blood vessel within the patient, such as the carotid artery, the renal artery and the coronary artery.
2. Discussion of the Prior Art
A number of procedures have been suggested in the past for opening stenosed or occluded blood vessels in a patient caused by the deposit of plaque or other material on the walls of the blood vessels. For example, angioplasty, is a well known procedure wherein an inflatable balloon is first introduced into the occluded region and then inflated, dilating the stenosed blood vessel in the manner to increase the intraluminal diameter.
Another well-known prior art procedure involves permanently or temporarily introducing a stent into the stenosed region to open the lumen of the vessel. The stent, which is readily commercially available from various sources, typically comprises a generally cylindrically shaped mesh sleeve made from such materials as stainless steel or nitinol. The unique design of the stent permits it to be radially expanded, while still providing sufficient rigidity to maintain its shape once it has been expanded to a desired size.
In the practice of the prior art stent emplacement procedures, the stent is introduced into the desired blood vessel using known percutaneous methods. More particularly, a catheter, having the stent affixed thereto, is directed to the region of the blood vessel being treated and is strategically positioned so that the stent is centered across the stenosed region. This done, the balloon is inflated, by introducing gas or fluid, through a lumen in the catheter communicating with the balloon. The controlled inflation of the balloon causes the stent to expand radially outward into engagement with the stenosed material. As the stent expands, the material is forced outward, dilating the lumen of the blood vessel. Once in position, the stent retains its expanded shape, providing an open passage for blood flow. The balloon is then deflated and the catheter withdrawn from the vessel.
During the stent emplacement procedure, plaque that has been deposited on the walls of the vessel may be set free and when this material travels downstream, it can cause serious complications. By way of example, loose embolic material released within the carotid arteries may travel downstream to the brain, possibly causing stroke, which can lead to permanent injuries and sometimes the death of the patient.
Thus, there is a need for an apparatus and method for delivering a stent into an arterial occlusion, which effectively prevents loose embolic material from traveling downstream and also prevents blood and embolic material from flowing through the guide wire lumen of the stent delivery catheter a direction toward the proximal end of the catheter.
In typical prior art balloon angioplasty procedures, a guiding catheter having a preformed distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient in accordance with conventional techniques. The guiding catheter is then advanced within the cardiovascular system until the distal tip is seated in the ostium of a desired coronary artery. A guide wire is positioned within an inner lumen of a dilatation catheter and then both are advanced through the guiding catheter to the distal end thereof. The guide wire is first advanced out of the distal end of the guiding catheter into the patient's coronary vasculature until the distal end of the guide wire crosses a lesion to be dilated, then the dilatation catheter having an inflatable balloon proximate the distal end thereof is advanced into the patient's coronary anatomy over the previously introduced guide wire until the balloon of the dilatation catheter is properly positioned across the lesion. Once in position across the lesion, the balloon is inflated to a predetermined pressure to compress the arteriosclerotic plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilatation catheter can be removed.
Applicant is familiar with a prior art distal protection system that is available from Medtronic, Inc of Minneapolis, Minn. that is sold under the name and style “GUARDWIRE PLUS”. This system, which contains the balloon at its the distal tip, is deployed across the lesion and is then inflated to occlude the vessel and prevent migration of embolic particles that may become dislodged during an intervention. The angioplasty balloon and stent systems are then advanced to the treatment side, where the dislodged large particles remain suspended in the occluded vessel. Upon completion of the interventional procedure, another catheter is introduced and the particles are aspirated. This done, the balloon is deflated and removed.
Applicant is also familiar with a prior art, balloon protected flush extraction system offered by the Kensey Nash Corp. of Exton, Pa. under the name and style “TRIACTIV”. This system uses three distinct components, namely a guide wire with the distal protection balloon, a flexible 3 French flush catheter and active peristaltic pump flush and extraction systems. These three features work in concert to provide distal protection with debris extraction. Following stenting the protected space is flushed and any remaining loose debris is extracted.
Another prior art distal protection device is offered for sale by the Traatek Company of Miami, Fla. under the name and style “PERCUSURGE”. This device is a balloon the occlusion thrombectomy device approved by the United States Food and Drug Administration for vein graft intervention.